Be prepared to see this sight all over the Merrieather Post Pavilion grounds on Sept. 10. (Three Six Zero Group)

1. Where’s the headliner?

Consider this a trend. The first FreeFest featured Blink-182 and Weezer, a pair of arena/pavilion-level bands. But they were touring together and the D.C. stop was basically expanded and turned into FreeFest. Last year’s headliners — LCD Soundsystem, M.I.A. and Pavement — aren’t arena bands. (Unless they are playing a farewell show in their hometown.) This year’s de facto headliner, the Black Keys, played Constitution Hall last time in town. All the other acts would likely make 9:30 Club the local tour stop.

(Five more observations, after the jump.)

2. Electronic takeover

This year’s FreeFest features some big names that specialize in big beats — Deadmau5, Cut Copy and Empire of the Sun. And those three acts will all be performing on the festival’s main stages, not relegated to the dusty Dance Forest. The Forest, with a lineup featuring James Murphy, Calvin Harris, Ghostland Observatory and !!!, will likely be packed most of the day.

3. Familiar faces

Now in its sixth year, it makes sense that we’ll start to see lots of Virgin Festival repeaters. Black Keys played in 2008. So did Deadmau5. Cee Lo Green played with Gnarls Barkley in 2006. James Murphy is (we think?) the first Virgin Festival three-timer, as LCD Soundsystem played in both ‘07 and ‘10.

4. Be prepared to see lots of teenagers wearing rabbit ears

We got a very small taste of this on Saturday at the Animal Collective show. But it will be inescapable at FreeFest thanks to Deadmau5’s presence. Check out this photo gallery from a recent New Orleans show to get a taste of what to expect.

5. Where’s the local act?

In 2009 there was Wale. Last year there was Thievery Corporation and Will Eastman. (And, sort of, Joan Jett.) But there’s nothing resembling a local act in 2011. It seems like there would be room in the Dance Forest for some of the D.C.-bred talent that has made U Street Music Hall one of the country’s hottest clubs. No Nadastrom? Can’t we get some moombahton in there somwhere?

6. Self-assessment: Solid “B” on our predictions

So the Foo Fighters will not be playing, that was a big whiff. But the Sept. 10 date was correct and four of the top-billed acts — Black Keys, Cee Lo Green, TV on the Radio and Cut Copy — were predicted. Not perfect, but decent enough.